 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.internal.expressions;

 import org.eclipse.core.runtime.Assert;
 import org.eclipse.core.runtime.CoreException;

 import org.eclipse.core.expressions.EvaluationResult;
 import org.eclipse.core.expressions.Expression;
 import org.eclipse.core.expressions.ExpressionInfo;
 import org.eclipse.core.expressions.IEvaluationContext;

 public class NotExpression extends Expression {
     /**
      * The seed for the hash code for all not expressions.
      */
     private static final int HASH_INITIAL= NotExpression.class.getName().hashCode();

     private Expression fExpression;

     public NotExpression(Expression expression) {
         Assert.isNotNull(expression);
         fExpression= expression;
     }
     
     public EvaluationResult evaluate(IEvaluationContext context) throws CoreException {
         return fExpression.evaluate(context).not();
     }
     
     public void collectExpressionInfo(ExpressionInfo info) {
         fExpression.collectExpressionInfo(info);
     }

     public boolean equals(final Object object) {
         if (!(object instanceof NotExpression))
             return false;
         
         final NotExpression that= (NotExpression)object;
         return this.fExpression.equals(that.fExpression);
     }

     protected int computeHashCode() {
         return HASH_INITIAL * HASH_FACTOR + fExpression.hashCode();
     }
 }

